Frequency Modulated/Continuous Wave (FM/CW) Radar Altimeters need ways in which to verify proper operation and accuracy of data supplied to aircraft flight controls. In the current radar altimeters, self-calibration is performed in an open loop manner using Bulk Acoustic Wave (BAW) devices. The present open loop design requires hand turning of a Voltage Control Oscillator (VCO) based on an analysis of the outputted signal as compared to an expected signal. Components of the open loop system, such as the BAW are relatively expensive and fail to allow detection of non-linearities in tuning, absolute frequency errors, frequency drift versus temperature, and receiver amplitude/phase errors.
Therefore, there exists a need to replace expensive BAW devices and to implement a calibration system that more effectively corrects inaccuracies.